REDWOOD SHORES, Calif. ( TheStreet -- Oracle's ( ORCL) $7.4 billion acquisition of Sun Microsystems ( JAVA) is facing stiff opposition from technology pressure groups on both sides of the Atlantic. The deal has already been approved by Sun shareholders and the Department of Justice but has been delayed while European regulators scrutinize the merger's antitrust implications. Officials are mainly concerned about Oracle getting its hands on Sun's MySQL database and thus limiting the choice for database software. MySQL, which competes with Microsoft's ( MSFT) SQL and IBM's ( IBM) DB2 technology, is regarded as the jewel in Sun's crown. The technology, however, also features in free software projects such as WordPress, prompting concern that the deal could have widespread ramifications for the broader tech sector. Knowledge Ecology International, a social justice organization founded by Ralph Nader, is now pressuring the European Commission to veto the Oracle/Sun merger, along with the U.K.-based Open Rights Group and "software freedom" activist Richard Stallman. In a letter to European Competition Commissioner Neelie Kroes, the groups warned that Oracle's Sun acquisition could have dire consequences for software developers. "Oracle seeks to acquire MySQL to prevent further erosion of its share of the market for database software licenses and services, and to protect the high prices now charged for its proprietary database software licenses and services," he wrote. "If Oracle is allowed to acquire MySQL, it will predictably limit the development and functionality of the MySQL platform." The database giant's Sun acquisition sent shockwaves through the tech sector when it was announced earlier this year. The tech bellwether has not yet responded to TheStreet's request for comment on this story, although fiery Oracle chief Larry Ellison recently urged customers to have faith in the acquisition.